Garage Door Insulation — Part 2 (Reflectix radiant heat barrier)

After installing the R-8 fiberglass batt with white vinyl backing, my garage doors were relatively well insulated, but I decided to add a layer of reflectix as a radiant heat barrier.

In this situation, with one side facing the open air of the garage, it adds about a 3 to the R factor. I also like the aesthetics of the silver bubblewrap more than the white puffy vinyl.

Unfortunately, unlike the Dow Corning fiberglass batt which is designed for garage doors and comes pre-cut at the factory to the correct height, I had to measure and cut the reflectix down from a 24 inch roll.

If you don’t have support bars, it’s relatively easy to install. Just make a few cuts to go around the upright bars and tuck the top and bottom inside the lips of the door panels. I was going to move the white plastic clips that hold the fiberglass in to outside the reflectix, but so far, a pure friction fit is holding it just fine.

The panels with support bars require more work. I guess it would be possible to remove the support bars and then re-install them on top of the reflectix, but I chose to measure and mark each bar location by cutting the edge of the reflectix, then taking it down and cutting the proper length. I installed the reflectix panel under the horizontal support bar, and made sure that the top lined up just under the height of the panel. Then I notched around the vertical bars so that I could get the top in place.

So far, they all stay in place with nothing more than a friction fit. The bottom panels that don’t have a horizontal support bar holding the reflectix bow the most when overhead and may pose a problem as they age, but if I run into issues, I’ll just take the plastic clips that hold the fiberglass on and move them to the outside of the reflectix to help hold it in place as well.

Next, I’m going to cut aluminum faced polyiso foam insulation for the spaces around the windows in the top panels.

4 thoughts on “Garage Door Insulation — Part 2 (Reflectix radiant heat barrier)

  1. Pingback: Garage Insulation – Part 1 (Fiberglass door insulation) | Jay's Technical Talk

  2. Hi Jay
    Thanks for the nice insulation videos to insulate your garage.
    My concern is the weight. I have a 3 car garage – one double door and one single door – aluminum.
    Do you think the added weight will be an issue for the double door? I don’t want to tax my garage door opener.

    Thanks again.

    • The fiberglass/Reflectix and Foam are all very light.

      I don’t know the ratings of your garage door openers, but I didn’t notice any difference in the behavior of mine after adding the insulation. Unless your current openers are struggling now, I don’t think it will be an issue.

      (If your single door has the same opener as the double door, the single door opener will definitely have enough extra power to open the door along with added insulation.)

  3. Pingback: Garage Door Insulation part 3 – Window Openings | Jay's Technical Talk

Leave a Reply

Your email address will not be published.